Does anyone know what this might be? It is only on the bottom of my 18 inch round pool. I’ve had my above ground pool for three years and never had a problem. I’m in southern NJ. Right now the pollen has been absolutely awful so I’m not sure if that’s what I’m seeing. It does vacuum quickly and when moved with a brush quickly dissipates in the water without leaving a cloud. I had the water checked Saturday, 3 days ago and below are the numbers. They had me add 1/2 pound ph minus and 1 lb of calcium hydrochlorite. Right after that is when this stuff started. Chlorine level right now is testing very high. I don’t see the grayish matter in the morning when the filter is off.
FC 1.53
TC 1.53
PH 7.7
ALK 160
Adjust ALK 125
Hardness 260
CYA 105
We do things differently from pool stores and the other "established" numbers/levels for chemicals. The main difference is that we A) don't have anything to sell you, so you can use cheaper chemicals that have the same ingredients as the ones you buy from pool stores, and B) we recognize that there's a relationship between CYA and FC - the higher your CYA levels, the more FC you need to keep the water sanitary and algae-free.
The real key to all of this is doing your own testing. Pool store testing is wildly inaccurate so often, that it's really impossible for us to give you advice based on their testing. To do your own tests, you really need an FAS-DPD chlorine test kit and dropper/titration testing. There are two main kits in the US we recommend - the TFT-100 from tftestkits.net or the Taylor K-2006C that you can get from Amazon and other online retailers. (For what it's worth, I originally got the Taylor K-2006C and wish I would have gotten the TFT-100 - the K-2006C has a lot of extra tests you don't need as much, whereas the TFT-100 is more aimed at individual owners.)
The kits cost about $70-$100 or so, but you will more than save that if you follow our advice and stay out of the Pool Store for chemicals.
If you want to follow our methods, here's a few starting points (aside from the test kits):
Until your kit comes in, I'd add 3ppm of chlorine with liquid chlorine daily until the kit arrives. You can get liquid chlorine in various strengths - at 6% it's called regular household bleach (don't use Clorox or anything that says "splashless" or "scented", you want plain bleach) and at 10% or 12.5% it's called "liquid shock", "liquid chlorine", "pool shock" that comes in a jug, etc.
Once you get your kit, you can run the tests and we can help you. Hopefully the pool store provided CYA of 105 is a testing error on their end, or you'll likely need to exchange out about half the water or a bit more to bring CYA down so that your FC can work at a reasonable level.
Also, if you could put your pool info in your signature, it would help us with knowing your situation a bit better - see here:
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Does anyone know what this might be? It is only on the bottom of my 18 inch round pool. I’ve had my above ground pool for three years and never had a problem. I’m in southern NJ. Right now the pollen has been absolutely awful so I’m not sure if that’s what I’m seeing. It does vacuum quickly and when moved with a brush quickly dissipates in the water without leaving a cloud. I had the water checked Saturday, 3 days ago and below are the numbers. They had me add 1/2 pound ph minus and 1 lb of calcium hydrochlorite. Right after that is when this stuff started. Chlorine level right now is testing very high. I don’t see the grayish matter in the morning when the filter is off.
